Process for forming a pattern using a resist composition having a siloxane-bond structure

ABSTRACT

The present invention provides a composition having sensitivity to light or radiation. The composition comprises a polymer having a siloxane-bond structure which undergoes polymerization reaction when irridiated with light or radiation, and a sensitizing agent. The present invention also provides a process for forming a pattern, preparing a photomask and a semiconductor device by using the composition of the present invention.

This application is a division of application Ser. No. 08/304,086, filedSep. 9, 1994, (status: pending) which is a continuation of applicationSer. No. 08/135,952, filed Oct. 13, 1993, now U.S. Pat. No. 5,378,585,which is a continuation of application Ser. No. 07/719,188, filed Jun.21, 1991, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a composition having sensitivity tolight or radiation, wherein the term "light" or "radiation" hereinafterrepresents visible light, ultraviolet rays, far ultraviolet rays,X-rays, and electron beam, or an ion beam, a process for forming apattern, a method for preparing a photomask, and a method formanufacturing a semiconductor device by using the same.

2. Description of the Prior Art

There has arisen a demand for the formation of a predetermined fineresist pattern in the lithography process because of the tendency towardminiatuarization of semiconductor devices in recent years. In thelithography process, a resist film applied to a substrate is exposed tolight through a mask possessing light non-transmissive portions andlight transmissive portions. In this process, light is emitted from anexposure and reduction projection apparatus, through a pattern on a maskwhich is reduced by means of a lens, and then transfers such a patternto the resist film.

FIG. 16(a) represents the chemical formula of the main component of aconventional resist.

The above resist material is mainly compose of a polymer materialsoluble in an alkali aqueous solution such as novolak resin or phenolresin. In addition to this polymer, a sensitizing agent such as anaphthoquinonediazide compound is mixed therein to provide a resistmaterial having sensitivity to light or radiation. For this resistmaterial, an alkali aqueous solution, mainly, several percent ammoniumhydroxide aqueous solution, is used as a developer. When irradiated withlight or radiation, the naphtoquinone compound as a sensitizing agentproduces a carboxylic acid which dissolves in an alkali aqueous solutionas a developer to form a resist pattern. Consequently, the resistmaterial which contains a naphtoquinone compound may serve as a positivetype of resist material.

However, since the above resist material having sensitivity to light orradiation has low sensitivity as a resist, it needs to be irradiatedwith a relatively large amount of light or radiation so as to becomesoluble in a developer. The entails a deficiency in that the formationof the desired resist pattern requires the resist material to beirradiated with light or radiation for a relatively long period of time.Since the resist material has high absorbance to ultraviolet rays, ithas another deficiency of being unsuitable for lithography with the useof light with a shorter wavelength such as far ultraviolet rays.

In order to overcome the above deficiencies, a resist which is referredto as a chemically sensitizable resist has been developed. The materialfor this resist comprises a sensitizing compound which produces an acidwhen irradiated with light or radiation (an acid producing agent), and acompound which undergoes a chemical reaction under the presence of anacid. Therefore, the dissolving rate of the resist in a developer is notdirectly changed by the presence of an acid resulting from an acidproducing agent irradiated with light or radiation as a sensitizingagent, but changed by the reaction of other resist components catalyzedby the resulting acid. In such a resist, the change in a sensitizingagent induced when irradiated with light or radiation is amplified bycatalysis of the acid, thereby making a resist having high sensitivity.

Such a chemically sensitizable resist is described in U.S. Pat. No.4,491,628. The resist comprises a tert-butyl ester polymer as a maincomponent and onium salt as an acid producing agent. FIG. 16(b) shows anexample of the chemical formula of the components of the resist whichuses tert-butoxycarbonyloxystyrene as tert-butyl ester, andtriphenylsulfonium fluorouantimonate as an acid producing agent. In thisresist, when irradiated with light or radiation, the onium salt producesan acid which catalyzes hydrolysis of tert-butyl ester, thereby changingthe property of the irradiated portions of a resist film from lipophilicproperty to hydrophilic property. Consequently, the irradiated portionsof the resist film dissolves in a developer to form a resist pattern.

However, because of the trend for a fine structure in semiconductordevices in recent years, a fine resist pattern cannot be formed on asubstrate with a large difference in level even by the use of the abovechemically sensitizable resist.

For overcoming such a deficiency, multilayer resist methods have beendeveloped. In these methods, a thick organic film is formed on asubstrate to level the uneven surface of the substrate, on which a thinresist film is provided, after which the resist film is irradiated withlight or radiation to form a resist pattern. Thereafter, by the use ofthe resist pattern as a mask, the lower thick organic film is etched bymeans of dry etching, thereby transferring the resist pattern to theorganic film. According to these multi-layer resist methods, theresolving power of the resist can be maintained, and prevented fromdecreasing due to the variety of the depth of focus, thereby forming afine resist pattern on the substrate with a large difference in level.Examples of multilayer resist methods include two methods as follows:

One is a three-layer resist method, wherein in order to transfer aresist pattern to a lower thick organic film, an intermediate layer suchas a silicon dioxide film having a resistance to dry etching with oxygenis interposed between the lower thick organic film and the upper resistfilm.

Another is a two-layer resist method, wherein a material having aresistance to dry etching with oxygen serves as an upper resist film.

The later two-layer resist method is more promising because of itseasier process as compared to the former three-layer resist method. Mostof the resist materials used in the two-layer method contains silicon.Since silicon is stable to oxygen plasma for use in dry etching, thesilicon-containing resist film is scarcely removed by etching.Consequently, only the lower thick organic film can be etched by oxygenplasma through a silicon-containing resist pattern as a mask, therebytransferring a resist pattern with high resolution to the organic film.

The silicon-containing resists used in the two-layer resist method maybe classified into three kinds as follows: (1) a polymerizableone-component resist, (2) a two-component resist containing anaphthoquinone compound as a sensitizing agent, and (3) a chemicallysensitizable resist.

(1) An example of a polymerizable one-component resist containingsilicon is described in Jpn. J. Appl. Phys. (pages L659-660, vol. 22,1983, by M. Morita, et.al.), which is an SNR (Silicon-based NegativeResist) having polysiloxane bonds as shown in FIG. 17(a). This resisthas sensitivity to an electron beam and far ultraviolet rays as anegative type of resist. The sensitivity to an electron beam is 4.5μC/cm². An organic solvent such as a mixed solvent containingdiisobutylketone and cyclohexanone is used as a developer. In additionto this resist, many polymerizable one-component resists containingsilicon have been developed. For example, it has been reported in SPIE(pages 70-63, vol. 639, 1985, by R. G. Brault, R. L. Kubena and R. A.Metzger) that polysilsesquioxane having a trimethylsilyl group as an endgroup thereof as shown in FIG. 17(b) may serve as the one-componentresist. The sensitivity to an electron beam of this resist is 40 μC/cm².An organic solvent such as ethyleneglycolmonoethylether is used as adeveloper.

(2) An example of a two-component resist comprising a naphthoquinonecompound as a sensitizing agent and a silicon-containing resin which issoluble in an alkali solution as a base polymer is described in J.Electrochem. Soc. (pages 903-913, vol. 132, 1985, by Y. Saotomo, etal.), which comprises, for example, a novolak resin that contains atrimethylsilylmethyl group shown in FIG. 17(c) as a base polymer and anaphthoquinone compound also shown in FIG. 17(c) as a sensitizing agent.Since the base polymer has a hydroxyl group, the resist is soluble in analkali aqueous solution. Therefore, an alkali aqueous solution such as asolution of tetramethylammonium hydroxide (TMAH) is used as a developer.

FIG. 17(d) shows a resist described in SPIE (pages 192-294, vol. 920,1988, by S. Imamura et al.), which comprises acetylatedpolyphenylsilsesquioxane as a base polymer, which is also soluble in analkali aqueous solution. Consequently, the resist may serve as apositive type of resist which may be developed by the use of an alkaliaqueous solution by adding a naphthoquinone compound as a sensitizingagent thereto. The sensitivity to ultraviolet rays of the resist is 100mJ/cm² for a g-line, and 40 mJ/cm² for an i-line.

In addition to these resists, many resists have been developed whichcomprises a naphthoquinone compound as a sensitizing agent, and asilicon-containing resin which is soluble in an alkali solution as abase polymer. These resists are characterized in that they can bedeveloped by an alkali solution and have a sensitivity of almost 100mJ/cm² because of the presence of a naphthoquinone compound as asensitizing agent.

(3) The chemically sensitizable resist has high sensitivity andtherefore it can form a resist pattern with high resolution. An exampleof a resist is described in Japanese Laid-Open Patent Publication No.60-52845. A resist comprising a compound that produces a cation or ananion when irradiated with light or radiation as a sensitizing agent,and a resin that reacts with the resulting cation or anion moiety torelease a silyl group therefrom as a base polymer is known. An exampleof the main component of this resist is shown in FIG. 16(e), whichcomprises onium salt as the compound that produces an acid whenirradiated with light or radiation, and polytrimethylsiloxystyrene asthe polymer which releases a silyl group therefrom.

An example of a resist having the same structure as stated above isdescribed in Proc. Microcircuit Engineering (page 471, 1984, by F.Buiguez, et.al.), which has sensitivity to ultraviolet rays (wavelength:436 nm) due to the addition of perylene (C₂₀ H₁₂) as a sensitizer. FIG.17(f) further shows a resist described in SPIE (pages 13-20, vol. 920,1988, by A. Steinmann et.al.), which comprises onium salt as thecompound that produces an acid when irradiated with light orirradiation, and polytrimethylsilylphthalaldehyde as a base polymer.Since the onium salt has sensitivity only to far ultraviolet rays (<300nm), perylene is added to this resist material as a sensitizer so thatthe resist may have sensitivity to a g-line (436 nm).

However, the above silicon-containing resists have deficiencies asdescribed below.

(1) In the case of a polymerizable one-component resist, an organicsolvent is used as a developer in a process of development afterexposure. At present, the development by the use of an organic solventas a developer requires higher cost than that by the use of an alkaliaqueous solution as a developer for conventional photoresists. While analkali developer after dilution with water will not adversely affecthuman, an organic solvent is insoluble in water, and requireslarge-scale equipment for decomposition. These entail problemsassociated with safety in the operation thereof and pollution.

In development by the use of an organic solvent as a developer, thedeveloper penetrates the remaining portions of a resist corresponding toa resist pattern, this makes the resist swollen, thereby lowering theresolution of the resist pattern.

(2) A two-components resist comprising a naphthoquinone compound as asensitizing agent and a silicon-containing resin which is soluble in analkali solution as a base polymer can be developed by the use of analkali aqueous solution. However, since this resist comprises the samenaphthoquinone compound as that in conventional photoresists as asensitizing agent, it has the same level of sensitivity to light asconventional photoresists, which is difficult to be raised.

Since the naphthoquinone compound also has high absorbance to light ofshort wavelength, the resist is not suitable for lithography by the useof light of short wavelength. The resolution of this kind ofconventional resists is not entirely satisfactory, because thedissolving rate of the silicon-containing resin in an alkali solution ofa developer has not been optimized.

(3) The chemically sensitizable resists containing silicon has adeficiency in that the resist pattern is also etched with an lower layerduring an etching process because of the small content of silicon in theresist. FIG. 9 shows the relationship between the silicon content of theupper resist film and the selection ratio of the etched lower resistfilm to the etched upper resist film. The data in FIG. 9 is plotted,with the silicon content as abscissa and the selection ratio as theordinate. When no silicon is contained, the selection ratio with respectto dry etching is zero, indicating that etching of the upper resist filmproceeds. With an increase in the silicon content of the upper resistfilm, the selection ratio increases, thereby improving the resolution ofa transfered resist pattern. The silicon content ofpolytrimethylsiloxystyrene shown in FIG. 17(e) is 14%, and the siliconcontent of polytrimethylsilylphthalaldehyde shown in FIG. 17(f) is 20%.However, both silicon contents are not sufficient to obtain highresolution, thereby requiring the use of a base polymer having highersilicon content.

SUMMARY OF THE INVENTION

The composition having sensitivity to light or radiation of thisinvention, which overcomes the above-discussed and numerous otherdisadvantages and deficiencies of the prior art, comprises:

a base polymer consisting essentially of a polymer having asiloxane-bond structure; and

a sensitizing agent.

In a preferred embodiment, the polymer having a siloxane-bond structureundergoes polymerization reaction when irradiated with light orradiation.

In a preferred embodiment, the polymer having a siloxane bond structurehas at least one end group or said chain group which undergoescondensation polymerization produced from the sensitizing agent byexposure to light or radiation.

In a preferred embodiment, the polymer having a siloxane-bond structureundergoes condensation polymerization by catalysis of an acid or aradical.

A composition having sensitivity to light or radiation, comprises:

a base polymer consisting essentially of a polymer having asiloxane-bond structure, a sensitizing agent, and dyes having highsolubility in a polar solvent.

A process for forming a pattern, comprises the steps of:

forming a smoothing layer on a substrate;

applying a composition having sensitivity to light or radiation of thepresent invention to the smoothing layer to form a resist film;

exposing of predetermined portions of the resist film to light orradiation; and

developing the resist film by the use of an alkali developer.

A method for preparing a photomask comprises the steps of:

applying a light non-transmissive pattern on a surface of a substrate,

applying a composition of the present invention over the surface of thesubstrate with said shading pattern to form a resist film,

exposing a predetermined portion of the resist film to light orradiation,

developing the resist film by the use of a developer, resulting in aphase shifter.

A method for preparing a photomask which further comprises:

The step of subjecting the phase shifter to a heating treatment tocomplete a polymerization reaction of the polymer contained in thecomposition of the present invention.

A method for manufacturing a semiconductor device, comprises the stepsof:

forming a semiconductor element on a substrate;

forming a plurality of bonding pads on part of the substrate;

forming a protective film to cover the entire surface of the substrate,

subjecting the protective film to an etching treatment to form windowson the portions of the protective film facing the individual bondingpads,

applying the composition of the present invention to the entire surfaceof the protective film, including the bonding pads, resulting a resistfilm,

exposing the resist film to light or radiation,

developing the resist film by the use of a developer, and

connecting the individual bonding pads to wires.

Thus, the invention described herein makes possible the objectives of:

(1) providing a composition having sufficient sensitivity to light orradiation which is suitable for lithography by the use of light of shortwavelength such as far ultraviolet rays;

(2) providing a composition having sensitivity to light or radiationwhich has high resolving power of a resist and can form a fine resistpattern even on a substrate with a large difference in level,

(3) providing a composition having sensitivity to light or radiationwhich can be developed by the use of a developer which is inexpensive,readily decomposed, safe for the handling thereof, and will not causepollution,

(4) providing a composition having sensitivity to light or radiation ofwhich the resolution of a resist pattern will not decrease due toswelling during development after exposure,

(5) providing a composition having sensitivity to light or radiationwhich has small absorbance to light of short wavelength, and

(6) providing a composition having sensitivity to light or radiation ofwhich a resist pattern will not be etched during a process of etchingand may transfer the resist pattern with high resolution.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention may be better understood and its numerous objects andadvantages will become apparent to those skilled in the art by referenceto the accompanying drawings as follows:

FIGS. 1(a) to 1(c) show diagrams representing the structures of polymerhaving a siloxane-bond structure.

FIGS. 2(a) and 2(b) show diagrams representing the structure of thecomposition having sensitivity to light or radiation of Example 1 of thepresent invention.

FIG. 3 shows a diagram representing the curves indicating thesensitivity to an electron beam of the resist from by the resistmaterials of Examples 1 of the present invention.

FIG. 4 is a graph representing the relationship between the molecularweight of the polymer having a siloxane-bond structure present in thecomposition of the present invention and the dissolving rate in adeveloper.

FIGS. 5(a) and 5(b) show diagrams representing the reaction mechanism ofthe composition having sensitivity to light or radiation of Example 1 ofthe present invention.

FIGS. 6(a) to 6(c) show diagrams representing the structure of thecomposition having sensitivity to light or radiation of Example 2 of thepresent invention.

FIGS. 7(a) and 7(b) show diagrams representing the structure of thecomposition having sensitivity to light or radiation of Example 3 of thepresent invention.

FIGS. 8(a) and 8(b) show diagrams representing the structure of thecomposition having sensitivity to light or radiation of Example 4 of thepresent invention.

FIG. 9 is a graph showing the relationship between the silicon contentand the resistance to dry etching of the polymer of the presentinvention.

FIG. 10 is a graph showing the light transmittance of a resist formedfrom the composition of the present invention.

FIG. 11 is a graph showing the thermal resistance of the resist formedfrom the composition of the present invention.

FIGS. 12(a) to 12(c) show diagrams illustrating a process for forming aresist by a two-layer resist method of the present invention.

FIGS. 13(a) to 13(c) show diagrams illustrating a process for preparinga phase shifting mask of the present invention.

FIGS. 14(a) to 14(c) show the other diagrams illustrating phase shiftingmasks prepared according to the process of the present invention.

FIGS. 15(a) to 15(d) show a diagram illustrating a process formanufacturing a semiconductor device of the present invention.

FIGS. 16(a) and 16(b) show diagrams representing the structures ofconventional resist materials.

FIGS. 17(a)-17(f) show diagrams representing the structures of the otherconventional resist materials.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The composition having sensitivity to light or radiation of the presentinvention will now be described.

The composition having sensitivity to light or radiation of the presentinvention comprises a base polymer consisting essentially of a polymerhaving a siloxane-bond structure and a sensitizing agent. In the presentinvention, the term "light" or "radiation" includes visible light,ultraviolet rays, far ultraviolet rays, vacuum ultraviolet rays, X-rays,gamma rays, an electron beam, an ion beam, etc.

The polymer having a siloxane-bond (--Si--O--) structure present in thecomposition of the present invention is polymerized due to exposure withlight or radiation. Examples of the polymer are as follows: asingle-chain-form of polysiloxane as shown in FIG. 1(a), a ladder-formof polysiloxane as shown in FIG. 1(b), and a polymer having a threedimensional structure of polysiloxane as shown in FIG. 1(c). In FIG. 1,R1 and R2 which are an organic group (a side chain group, i.e., a grouppresented at side chain group), and R3 and R4 which are an end grouppresent in a repeating unit, each of these groups can be a hydrogenatom, a hydroxyl group, a lower alkyl group having 1to 5 carbon atoms, alower alkoxyl group having 1 to 5 carbon atoms, a phenyl group, a benzylgroup, a phenoxy group, a benzyloxy group, a trialkylsilyl group, etc.

As stated above, the condensation polymerization is caused by an anionor a cation produced from the sensitizing agent by exposure to light orradiation. The polymer having a siloxane-bond structure contains atleast one side chain group or end group that is a functional group whichcauses this condensation polymerization. Examples of the functionalgroup include a hydroxyl group, an alkoxyl group, or a phenoxy group.The polysilsesquioxane, which is a particularly preferable material forresist, contains a hydroxyl group and an alkoxyl group in a ratio of 1to 1 as an end group, and an alkyl group or a phenyl group as a sidechain group. When the composition of the present invention comprising abase polymer consisting essentially of a polymer having a siloxane-bondand a sensitizing agent is used for a resist material, this resist willhave sufficient sensitivity to light and small absorbance to ultravioletrays, and therefore it is suitable for a lithography utilizing light ofshort wavelength. The resolving power of the resist can also bemaintained and prevented from decreasing due to the deviation of thedepth of the focus of light for use in exposure, thereby forming a fineresist pattern even on a substrate with a large difference in level. Thepolymer having a siloxane-bond structure undergoes condensationpolymerization when irradiated with light or radiation and becomesinsoluble in a solvent. When the composition having sensitivity to lightor radiation is used as a resist material by imparting polarity to theend group or the side chain group of the polymer having a siloxane-bondstructure present in the composition, not only an organic solvent butalso an alkali solution can be used as a developer, which leads to a lowcost developer, the easy disposal and the safe handling thereof, and nopollution. The use of an alkali solution may also prevent a resist fromswelling, thereby preventing the resolution of a resist pattern fromdecreasing.

When the composition of the present invention is used as a resistmaterial, in order to raise the resistance to dry etching, the contentof the polymer having a siloxane-bond structure of the composition is 10percent by weight or more, and preferably 50 percent by weight or more.When the polymer content of the composition is less than 10 percent byweight, the resistance to dry etching of the composition decreases,thereby lowering the resolution of the transferred resist pattern. Theabove polymer having a siloxane-bond structure is used as a base polymerin the composition of the present invention, which may comprise anadditional repeating unit such as styrene, α-methylstyrene,methylmethacrylate, methylacrylate, etc.

The process for preparing a polymer having a siloxane-bond structurewill now be described in detail by reference to examples.

(1) A process for preparing ladder-form silicone(polyorganosilsesquioxane)

Hydrolysis of a trifunctional silicon compound provides ladder-formsilicone as shown in FIG. 1(b). A case will now be described wheremethyltrichlorosilane is used as a trifunctional silicone compound. Onemole of methyltrichlorosilane and two moles of distilled water areheated with reflux for 4 hours by the use of hydrochloric acid in aconcentration of 2 ppm in a reactor with a reflux condenser, thus beinghydrolyzed and condensed, thereby undergoing polymerization. Thereafter,the resulting solution is filtered, and the filtered substance is thendissolved in butanol to prepare a solution of polymethylsilsesquioxane.The solution thus prepared is a solution of polymethylsilsesquioxanehaving a hydroxyl group as an end group as shown in FIG. 1(b), whereinR1 and R2 are a methyl group, and R3 and R4 are a hydroxyl group.

The above reaction is represented by the formula as follows: ##STR1##

By the use of phenyltriethoxysilane as a starting material, the samereaction as described above is conducted to preparepolyphenylsilsesquioxane as shown in FIG. 1(b), wherein R1 and R2 are aphenyl group, and R3 and R4 are a hydroxyl group.

Further, by the use of methyltriethoxysilane as a starting material, thesame reaction as described above is conducted to preparepolymethylsilsesquioxane which contains a hydroxyl group and an ethoxygroup as an end group each in the same amount shown in FIG. 1(b),wherein R1 and R2 are a methyl group, and R3 and R4 are eachindependently a hydroxyl group or an ethoxy group.

The above reaction is represented by the formula as follows: ##STR2##

(2) The process for preparing a chain of silicone (polyorganosiloxane)

Hydrolysis of a bifunctional silicon compound provides a chain ofsilicone shown in FIG. 1(a). For example, hydrolysis and condensation ofdimethyldichlorosilane provides polydimethylsiloxane which has ahydroxyl group as an end group as shown in FIG. 1(a), wherein R1 and R2are a methyl group, and R3 is a hydroxyl group.

(3) The process for preparing a three dimensional silicone network.

Hydrolysis of a tetrafunctional silicon compound provides threedimensional silicone chain network as shown in FIG. 1(c). For example,hydrolysis and condensation of tetrachlorosilane provides polysiloxanewhich has a hydroxyl group as an end group as shown in FIG. 1(c),wherein R3, and R4 are a hydroxyl group.

When the functional group of a silicon compound as a starting materialis chlorine, any type of polysiloxane obtained have hydroxyl groups asend groups as shown in FIG. 1, wherein R3 and R4 are a hydroxyl group.On the other hand, when the functional group is an alkoxy group (in theabove formula, an ethoxy group), an hydroxyl group and an alkoxy groupare present each in almost the same amount as an end group of theresulting polysiloxane.

As described above, a starting material may appropriately be selected tobe polymerized so as to provide polysiloxane having the desired sidechain groups, the desired end groups, and the desired frame-work ofsiloxane bonds according to objective thereof.

A polymer having a siloxane-bond structure may be selected from a chainform, ladder form, or three dimensional form of polymer network, whereina side chain group is a group represented by R1 and R2 shown in FIG. 1,and an end group is a group represented by R3 and R4 shown in FIG. 1.

As a sensitizing agent present in the composition of the presentinvention, a substance which produces an acid or a substance whichproduces a radical when irradiated with light or radiation is used.

Examples of the sensitizing agent (an initiator or an acid producingagent) which produces an acid when irradiated with light or radiationinclude (1) to (3) described below. However, any compounds which produceacids when irradiated with light or radiation may be used. The compoundswhich produce acids by photolysis thereof described in U.S. Pat. No.3,779,778 and Japanese Laid-Open Patent Publication No. 63-236028 mayalso be used in the composition of the present invention.

Onium salt

Onium salt produces a Br.o slashed.nsted acid when irradiated with lightor radiation. Examples of the onium salt include diaryliodonium salt(Ar₂ I⁺ X⁻), triarylsulfonium salt (Ar₃ S⁺ X⁻), triarylselenium salt(Ar₃ Se⁺ X⁻), wherein aryl (Ar) is mono- to tri- substituted ornon-substituted benzene having a methyl group, a methoxy group, at-butyl group, a nitro group, chlorine, or a CH₃ CONH-- group, etc., asa substituent group, and an anion X⁻ is PF₆ ⁻, AsF₆ ⁻, SbF₆ ⁻, BF₄ ⁻,ClO₄ ⁻, CF₃ SO₃ ⁻, FSO₃ ⁻, F₂ PO₂ ⁻, etc.

(2) Diazonium salt

Aryldiazonium salt (ArN₂ ^(+X) ⁻) produces a Lewis acid when irradiatedwith light or radiation, wherein aryl (Ar) is mono- to tri- substitutedor non-substituted benzene having a methyl group, a methoxy group, amorpholino group, a nitro group, chlorine, as a substituent group, andan anion X⁻ is PF₆ ⁻, AsF₆ ⁻, SbF₆ ⁻, BF₄ ⁻, FeCl₄ ⁻, SbCl₆ ⁻, SnCl₆ ⁻,etc.

(3) Sulfonate

Sulfonate produces a sulfonic acid when irradiated with light orradiation, such as α-hydroxymethylbenzoinsulfonate,N-hydroxyimidosulfonate, α-sulfonyloxyketone, β-sulfonyloxyketone,p-nitrobenzyldiethoxyanthracenesulfonate, o-nitrobenzyl tosylate,benzoin tosylate.

Examples of the sensitizing agent (the initiator) which produces aradical when irradiated with light or radiation present in thecomposition of the present invention include (1) to (3) described below.However, any compounds which produce radicals when irradiated with lightor radiation may be used.

(1) Aromatic ketone

Aromatic ketone

Aromatic ketone such as benzophenone, thioxanthone, quinone,thioacridone, produces a radical when irradiated with light orradiation.

(2) Polyhalogenated hydrocarbon

Polyhalogenated hydrocarbon such as CBr₄, CCl₄, RCCl₃, RCBr₃, wherein Ris a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group,produces a radical when irradiated with light or radiation.

(3) A triazine compound

A triazine compound (C₃ H₃ N₃), the 1 to 3 atoms of hydrogen moiety ofwhich is substituted with a trichloromethyl group (CCl₃ ⁻) also producesa radical when irradiated with light or radiation. Examples of thecompound include 2,4,6-Tris(trichloromethyl)-1,3,5-triazine,2,4-Bis(trichloromethyl)-6-(p-methoxyphenyl)-1,3,5-triazine), etc.

When the composition of the present invention is used as a resistmaterial by adding the above sensitizing agent that produces an acid ora radical when irradiated with light or radiation thereto, the resultingacid or the radical catalyzes the condensation polymerization of theabove polymer having a siloxane-bond structure.

The content of the above sensitizing agent is preferably 40 percent byweight or less based on the weight of the base polymer. When thesensitizing agent content is 40 percent by weight or less based on theweight of the base polymer, the resistance to dry etching of thecomposition decreases, thereby degrading the resolution of thetransferred resist pattern. The content of the above sensitizing agentdiffers depending on the kind of light or radiation for use in exposure,when irradiated with an electron beam, the sensitizing agent content ispreferably 10 percent by weight or less based on the weight of the basepolymer, and when irradiated with ultraviolet rays, the sensitizingagent content is preferably in the range of 0.2 to 10 percent by weightbased on the weight of the base polymer.

The process for forming a resist pattern made of the composition havingsensitivity to light or radiation of the present invention as a resistmaterial will now be described. Conventional process for forming aresist pattern comprises a step of forming a smoothing layer, a step offorming a resist film, a step of exposure, and a step of development.

First, a smoothing layer is formed by a conventional method in order tolevel the uneven surface of a silicon substrate. The aforesaidcomposition having sensitivity to light or radiation is dissolved in anorganic solvent to prepare a resist solution containing a solid in aconcentration in the range of 5 to 50 percent by weight. The resistsolution thus prepared is applied to the aforesaid leveled substrate bya spin coating process to form a film thereon. Then, the predeterminedportions of the film are irradiated with light or radiation. Thesensitizing agent in the irradiated portions produces an acid or aradical, which catalyzes a dehydration reaction or a de-alcoholizationreaction of a polymer having a siloxane-bond structure as the othercomponent of the resist film, thereby polymerizing the polymers. Then, adeveloper capable of dissolving the pre-polymerization polymer having asiloxane-bond structure is used, the polymerized portions is insolublein the developer, thereby forming a negative type of a resist pattern.By the use of the resulting resist pattern as a mask, the substrate isetched with suitable etchant, plasma, etc., to form a fine patternreflecting the resist pattern.

EXAMPLES

The present invention will now be explained in detail by reference tothe following examples.

Example 1

FIG. 2 shows resist materials of Example 1.

FIG. 2(a) shows polymethylsilsesquioxane having a siloxane-bondstructure having a methyl group as a side chain group, and a hydroxylgroup and an ethoxy group as an end group. This compound is used as abase polymer, or solely serves as a resist material.

FIG. 2(b) shows triphenylsulfonium triflate which is comprised in acomposition having sensitivity to light or radiation as a sensitizingagent (an initiator).

Hydrolysis and condensation of methyltriethoxysilane may providepolymethylsilsesquioxane as a base polymer. The number average molecularweight and the weight average molecular weight of the polymer are 1,310and 3,320, respectively.

The polymer is dissolved in an ethylalcohol/butylalcohol solvent mixture(weight ratio of ethylalcohol to butylalcohol is 1:1) to prepare asolution of 10 percent by weight. Thereafter, 1 to 5 percent by weightof triphenylsulfonium triflate is added as a sensitizing agent to theresulting solution based on the weight of the polymer to prepare aresist solution.

Table 1 shows samples of the resist solution each having differentconcentration of a sensitizing agent therein.

                  TABLE 1                                                         ______________________________________                                        Sensitivity to an electron beam and ultraviolet rays                          of the resist material of the present invention                                        Sensitizing Sensitivity to                                                                            Sensitivity to                                        agent       an electron ultraviolet                                           concetration                                                                              beam        rays                                         Sample   (wt %)      (μC/cm.sup.2)                                                                          (mJ/cm.sup.2)                                ______________________________________                                        Sample 10                                                                              0           8.0         >1000                                        Sample 11                                                                              1           0.30        40                                           Sample 12                                                                              2           0.25        35                                           Sample 13                                                                              3           0.20        30                                           Sample 15                                                                              5           0.18        27                                           ______________________________________                                    

These resist materials will now be each referred to as a sample 10, 11,12, 13, or 15 according to the concentration of the sensitizing agenttherein.

The resist solution is applied to a silicon substrate by a spin coatingprocess at a rate of 2,000 spin/min so that the resulting film has athickness of 0.5 μm. The resist film thus applied is dried by means of ahot plate at 75° C. for 2 minutes, after which the predetermined patternis drawn by means of an electron beam with an acceralation voltage of 25kV or far ultraviolet rays utilizing a Xe--Hg lamp as light source(exposure energy: 25 mW/cm²). Then, by the use of a 5% aqueous solutionof tetramethylammonium (TMAH) as a developer, dip development isconducted for 1 minute, which dissolved and removes the non-irradiatedportions to form a resist pattern at the removed portions.

Table 1 shows the sensitivity to an electron beam and the sensitivity tofar ultraviolet rays of each sample containing a sensitizing agent indifferent concentration.

Thus, Table 1 shows the measured values of the sensitivity to anelectron beam and the sensitivety to far ultraviolet rays of the resistmaterials each containing a sensitizing agent in differentconcentration. The sensitivity to an electron beam and the sensitivityto far ultraviolet rays used herein are defined as exposure which mayprovide a film with a thickness of 50% of the initial film thickness.

FIG. 3 shows curve indicating the sensitivity to an electron beam of thesamples 10 and 11 each containing a sensitizing agent in concentrationsof 0% and 1%, respectively.

As compared with the fact that SNR which is a conventionalsilicon-containing resist has a sensitivity to an electron beam in therange of 7 to 17 μC/cm², the resist formed in this example of thepresent invention is found to have much higher sensitivity. The sameexperiment indicates that all the resist formed from the resist materialof the samples 11, 12, 13, and 15 can resolve a line and space patternhaving a width of 0.5 μm with exposure amount in the range of 0.18 to0.3 μC/cm². The resolution is not found to be lowered due to swelling asis often found in the case of a negative type of resist.

Even sample 10 that is a resist material containing no sensitizing agentmay form a resist which has a sensitivity to an electron beam of 8μC/cm², which is as high as that of conventional resists. This indicatesthat the resist which comprises only a base polymer without asensitizing agent may independently serve as a resist material in thesame manner as conventional resist materials. Sample 10 is aone-component resist material, has relatively high sensitivity to anelectron beam and the high silicone content, and further can bedeveloped by the use of an alkali developer, thereby serving as a resistmaterial for an electron beam.

The weight average molecular weight of the polymer present in the sample10 is 3,230, and a 5% solution of TMAH is used as a developer.

FIG. 4 shows the relationship between the concentration of a TMAHaqueous solution and the dissolving rate of a polymer having asiloxane-bond structure (see FIG. 2(a)) in the solution. In FIG. 4, themark "•" denotes a sample of a polymer having a siloxane-bond structurehaving a molecular weight (Mw: weight average molecular weight) of7,044, and a molecular weight distribution (Mn/Mw: the ratio of numberaverage molecular weight to weight average molecular weight) of 2.1. Themark "o" denotes a sample of the polymer having a molecular weight of3,320 and a molecular weight distribution of 2.5. The mark ".increment."denotes a sample of the polymer having a molecular weight of 1,507 and amolecular weight distribution of 1.39.

The data shown in FIG. 4 indicates that the dissolving rate of all theabove polymers having a siloxane-bond structure having any molecularweight increases with an increase in the concentration of the TMAHsolution. The straight line indicated as 2.38% represents the pointswhere the concentration of the TMAH solution is 2.38%.

When the molecular weight of the polymer having a siloxane-bondstructure decreases, the dissolving rate of the polymer can be raisedonly when the concentration of the TMAH solution is raised. Therefore,when the concentration of the TMAH solution is held constant, thedissolving rate of the polymer decreases with a decrease in themolecular weight of the polymer. This phenomenon is largely differentfrom the dissolving property of conventional polymers as a resist.

Generally, as the molecular weight of a polymer decreases, thedissolving rate of the polymer increases. Therefore, with a positivetype of resist made of conventional radiation degradable polymers suchas PMMA, the molecular weight of the polymers at the irradiated portionsdecreases. On the other hand, with a negative type of resist made ofradiation crosslinkable polymers such as SNR, the molecular weight ofthe polymers at the irradiated portions increases. When the aboveresists are developed, while the portions where the molecular weight ofpolymers is small dissolves, the portions where the molecular weight ofpolymers is large remains. Thus, development is conducted by takingadvantage of the fact that while the portions where the molecular weightof polymers is large have a lower dissolving rate, the portions wherethe molecular weight of polymers is small has a high dissolving rate.

The dissolving property shown in FIG. 4 may be attributed to thechemical reaction between a TMAH solution and a polymer having asiloxane-bond structure. The polymer shown in FIG. 2(a) does not simplydissolve in the TMAH solution. The condensation reaction of the polymersis effected because of the presence of a hydroxyl group and an ethoxygroup both as an end group thereof by catalysis of TMAH which is analkali compound. That is, the polymers dissolve in the TMAH solution,while partially becoming insoluble.

When a polymer having a siloxane-bond structure which has low molecularweight and high content of end groups comes in contact with a TMAHsolution, the condensation reaction of the polymers rapidly proceeds dueto the change of dissolving property to insolubility. Therefore, at theportions where the molecular weight of polymers is 10,000 or less, a lowmolecular weight of polymer has a lower dissolving rate than a highmolecular weight of polymer.

In a process for manufacturing a semiconductor device, a 2.38% solutionof TMAH has been widely used as a developer for a photoresist.Therefore, a polymer which enables the development of the resist made ofsuch polymer by the use of a 2.38% solution of TMAH may be used in theprocess without changing conventional equipments and conditions formanufacturing a semiconductor. The resist formed from a resist materialcontaining the polymer having a siloxane bond structure of the presentinvention is a negative type of resist. Thus, if the dissolving rate ofthe polymer is 20 nm/sec or more, the resist may serve as a negativetype of resist.

FIG. 4 indicates that in order to obtain a dissolving rate of thepolymer of 20 nm/sec or more under a 2.38% solution of TMAH, themolecular weight of 3,320 of the polymer having a siloxane-bondstructure is too small to develop a resist. When the weight averagemolecular weight of the polymer which serves as a base polymer is 7.044,the dissolving rate of the polymer in the 2.38% solution of TMAH can besufficiently raised. Consequently, when the weight average molecularweight of a polymer made of the framework of siloxane bonds is 7.044,the resist made of the polymer may be developed to serve as a negativetype of resist.

A resist comprising the polymer having a siloxane-bond structure havinga weight average molecular weight of 7,044 as a base polymer may havethe same relationship between the concentration of a sensitizing agentand the sensitivity of the resulting resist as that shown in Table 1.

Further, since a polymer having a siloxane-bond structure having aweight average molecular weight of 1,507 has a glass transition pointlower than room temperature, when the resist material containing suchpolymer is applied to a substrate to form a resist film, the resultingresist film exhibits viscosity. Therefore, a polymer having asiloxane-bond structure having a weight average molecular weight of1,507 is not suitable for use as a base polymer. Consequently, in orderto use the polymer having a weight average molecular weight of 1,500 orless as a base polymer, the resulting resist film requires heattreatment at high temperature, etc., so as to facilitate thecondensation reaction thereof, thereby eliminating the viscosity.

As apparent from the above discussion, when a resist material comprisingthe polymer having a siloxane-bond structure of the present invention isindependently used as a resist for an electron beam, the weight averagemolecular weight of the polymer is preferably in the range of 2,000 to100,000, and more preferably in the range of 3,000 to 50,000. When asolution of 5 percent by weight or less TMAH is used as a developer, theweight average molecular weight of the polymer of the present inventionis preferably in the range of about 4,000 to about 20,000.

Table 1 indicates that the resist formed in this example of the presentinvention has very high sensitivity to far ultraviolet rays in the rangeof 20 to 40 mJ/cm².

By the use of this exposure apparatus, a line and space resist patternwith a width of 1 μm can be formed. This value indicates that a patternwith very high resolution is formed for contact exposure.

As stated above, the resist formed in this example of the presentinvention has high sensitivity to an electron beam and far ultravioletrays and high resolution. However, the onium salt used as a sensitizingagent of this example of the present invention has an absorption peak ataround 250 nm, and does not sensitize to light of a longer wavelengththan 313 nm. Therefore, the resist has no sensitivity to a g-line (436nm) and an i-line (365 nm) of a mercury lamp widely used at present in aprocess for manufacturing a semiconductor. The use of suitable organicdyes may impart the sensitivity of the resist to a g-line and an i-line.For preparing such a resist, to the resist material of a sample 11comprising 1 percent by weight of onium salt as a sensitizing agent isadded 3 percent by weight of phenothiazine (C₁₂ H₉ SN) as organic dyesto raise the sensitivity. This improves the sensitivity to a g-line to80 mJ/cm², and the sensitivity to an i-line to 60 mJ/cm².

Phanothiazine is used as organic dyes for improving the sensitivity,because perylene as conventional organic dyes for improving thesensitivity is insoluble in a mixed solvent containing ethylalcohol andbutylalcohol used as a solvent for the resist material, butphenothiazine has high solubility in such polar solvent.

The reaction mechanism of the composition having sensitivity to light orradiation will now be explained be reference to the resist formed fromthe resist material of the sample 11.

As shown in FIG. 5(a), when irradiated with light or radiation, theonium salt used as a sensitizing agent produces an acid. As shown inFIG. 5(b), the de-ethylalcoholization reaction of the hydroxyl group andthe ethoxy group both as an end group of polymethylsilsesquioxane usedas a base polymer is effected by catalysis of the resulting acid,thereby facilitating the polymerization of the polymer.

Generally, the solubility of a polymer decreases with an increase in themolecular weight of the polymer. Therefore, conventional polymerizableresists may serve as a negative type of resist by taking advantage ofthe property that some of the polymer constituting the resist becomesinsoluble in a developer because of an increase in the molecular weightthereof when irradiated with light or radiation.

The solubility of the resist of the present invention in an alkaliaqueous solution is mainly attributed to the presence of a hydroxylgroup as an end group of polymethylsilsesquioxane. The irradiatedportions of the resist rapidly becomes insoluble in a developer becauseof the progress of the reaction shown in FIG. 5(b). The irradiatedportions of the resist of the present invention becomes insolublebecause of an increase in the molecular weight, together with a changein the polarity of the polymers at the irradiat- ed portion. This maymarkedly increase a difference in the dissolving rate between theirradiated portions and the non-irradiated portions. Consequently, theresist of the present invention has a characteristic of very highsensitivity and high contrast property.

The number average molecular weight and the weight average molecularweight of the base polymer herein used are 1,310 and 3,320,respectively. Not limited to the present example, the weight averagemolecular weight of the polymer may preferably be in the range of 2,000to 500,000, and more preferably in the range of 3,000 to 100,000.

The molecular weight distribution, i.e., the value obtained by dividingthe weight average molecular weight by the number average molecularweight, is 2.5 in this example. However, it is desirable that themolecular weight distribution be close to 1 as much as possible.

FIG. 6 shows the resist materials of Example 2.

In these resist materials, polydiphenylsilsesquioxane having asiloxane-bond structure shown in FIG. 6(a) comprising a phenyl group asa side chain group and a hydroxyl group and an ethoxy group as an endgroup is a base polymer. Diphenyliodonium fluoroantimonate shown in FIG.6(b) is a sensitizing agent (an initiator), perylene (C₂₈ H₁₈) shown inFIG. 6(c) is used as a sensitizer. A composition having sensitivity tolight or radiation, which contains these materials, will now beexplained.

A resist material containing no sensitizing agent will be referred to asa sample 20, and a resist material containing a sensitizing agent and asensitizer each in an amount of 1 percent by weight will be referred toas a sample 21 hereinafter.

Hydrolysis and condensation of phenyltriethoxysilane providespolydiphenylsilsesquioxane as a base polymer. The number averagemolecular weight and the weight average molecular weight of the polymerare 1,900 and 3,420, respectively.

The above polymer is dissolved in butyl acetate to prepare a 10 wt. %solution. Then, to the resulting solution is added 1 percent by weightof diphenyliodonium triflate as a sensitizing agent and 1 percent byweight of perylene based on the weight of the polymer to prepare aresist solution.

The resist solution is applied to a silicon substrate by a spin coatingprocess at a rate of 2,200 spin/min so that the resulting resist filmhas a thickness of 0.5 μm. The resist film thus applied is dried bymeans of a hot plate at 75° C. for 2 minutes, after which by the use ofa stepper utilizing a g-line as light source (exposure wavelength: 436nm, the numerical aperture of a lens: 0.45) or a stepper utilizing ani-line as light source (exposure wavelength: 365 nm, the numericalaperture of a lens: 0.40), the resist film is exposed to ultravioletrays through a photomask having a predetermined light non-transmissivepattern. In both the above cases, radiation energy during exposure toultraviolet rays is 250 mW/cm². By the use of amethylethylketone/isopropylalcohol mixed solvent in a volume ratio ofmethylethylketone to isopropylalcohol of 1:1 as a developer, dipdevelopment is conducted for 1 minute.

Sample 21 has a sensitivity to a g-line of 12 mJ/cm² and a sensitivityto an i-line of 45 mJ/cm². The resist made of the resist material of thepresent invention may also have very high sensitivity to ultravioletrays (g-line, i-line) owing to the use of a sensitizer. Both exposuresabove can provide a line and space resist pattern with a width of 0.8μm.

In this case, development is conducted by the use of an organic solvent,but may also be conducted by the use of a TMAH aqueous solution.

EXAMPLE 3

FIG. 7 shows resist materials of Example 3.

In these resist materials, polydimethylsiloxane having a siloxane-bondstructure comprising a methyl group as a side chain group and a hydroxylgroup as an end shown in FIG. 7(a) group is used as a base polymer.2-(4'-methoxy-1'-naphthyl)-4, 6-bis(trichloromethyl)-1,3,5-triazineshown in FIG. 7(b) is a sensitizing agent (an initiator). A compositionhaving sensitivity to light or radiation which comprises these materialswill now be explained.

Hydrolysis and condensation of dimethyldichlorosilane providespolydimethylsiloxane as a base polymer. The number average molecularweight and the weight average molecular weight of the polymer are 1,960and 3,640, respectively.

The above polymer is dissolved in butylalcohol/ethylalcohol mixedsolvent (weight ratio of butylalcohol to ethylalcohol is 1:1) to preparea 10 wt. % solution. Then, to the resulting solution is added 1 percentby weight based on the weight of the polymer of the above triazinecompound as a sensitizing agent to prepare a resist solution. The resistsolution is applied to a silicon substrate by a spin coating process ata rate of 1,700 spin/min so that the resulting resist film has athickness of 0.5 μm. The resist film is dried by means of a hot plate at75° C. for 2 minutes, after which by the use of a stepper utilizing ani-line as light source (exposure wavelength: 365 nm, the numericalaperture of a lens: 0.40), the resist film is exposed to ultravioletrays through a photomask with a predetermined pattern. The radiationenergy during exposure to ultraviolet rays is 250 mW/cm². By the use ofa 2.38% solution of TMAH as a developer, dip development is conductedfor 1 minute. The sensitivity to an i-line of this resist is 33 mJ/cm².The above exposure may also provide a line and space resist pattern witha width of 1 μm.

EXAMPLE 4

FIG. 8 shows resist materials of Example 4.

In these resist materials, polyhydroxybenzylsilsesquioxane having asiloxane-bond structure comprising a hydroxylbenzyl group as a sidechain group and a hydroxyl group and an ethoxy group as an end group asshown in FIG. 8(a) is used as a base polymer, and O-nitrobenzyl tosylateshown in FIG. 8(b) is a sensitizing agent (an initiator). A compositionhaving sensitivity to light or radiation which contains these materialswill now be explained.

The above polymer is dissolved in butylalcohol/ethylalcohol mixedsolvent (weight ratio of butylalcohol to ethylalcohol is 1:1) to preparea 10 wt. % solution. Then, to the resulting solution is added 1 percentby weight based on the weight of the polymer of the above o-nitrobenzyltosylate as a sensitizing agent to prepare a resist solution.

The resist solution is applied to a silicon substrate by a spin coatingprocess at a rate of 2,100 spin/min so that the resulting resist filmhas a thickness of 0.5 μm. The resist film is dried by means of a hotplate at 75° C. for 2 minutes, after which by the use of an alignerutilizing a Xe-Hg lamp as light source, the resist film is exposed toultraviolet rays through a photomask with a predetermined pattern. Theradiation energy during exposure to ultraviolet rays is 250 mW/cm². bythe use of a 2.38% solution of TMAH, dip development is conducted for 1minute. The sensitivity to an i-line of this resist is 60 mJ/cm². Theabove exposure provides a line and space resist pattern with a width of1 μm.

In the above example, the base polymer having a weight average molecularweight of about 3,000 is described. The weight average molecular weightis not limited to this Example, it is preferably in the range of 500 to500,000, and more preferably in the range of 1,000 to 100,000. However,when development is conducted by the use of an alkali aqueous solution,the weight average molecular weight needs to be restricted up to about10,000. The molecular weight distribution, i.e., the value obtained bydividing the weight average molecular weight by the number averagemolecular weight is desirably close to 1 as much as possible.

In all of the Examples mentioned above, a sensitizing agent is containedin a concentration range of 0 to 5 percent by weight based on the weightof the base polymer. The concentration of sensitizing agent maypractically be in the range of 0 to 40 percent by weight. When theconcentration of sensitizing agent is high, the silicon content of theresist film decreases, which entails a problem in that the resistance toplasma etching is decreased as shown in FIG. 9. Since the polymer havinga siloxane-bond structure has excellent property as described below, itis desirable that the concentration of the sensitizing agent may belowered as much as possible in order to raise the polymer content of theresist film.

As described above, the polymer may have sufficient sensitivity to anelectron beam even with no sensitizing agent contained, thereby beingable to be used independently as a resist. However, a problem arises inthat the sensitivity to ultraviolet rays or far ultraviolet raysmarkedly decreases when the concentration of the sensitizing agentcontent is 0.2% by weight or less based on the weight of a base polymer.Therefore, it is necessary to vary the concentration of the sensitizingagent according to the end use thereof. As described above, when thepolymer is independently used as a resist, the property of the resist isdecided upon the balance between the sensitivity to light or radiationand the silicon content of the resist. When used as a resist for anelectron beam, the concentration of sensitizing agent in the range of 0to 10 percent by weight based on the weight of a base polymer is veryeffective as a resist, while when used as a resist for ultraviolet rays,the range of 0.2 to 10 percent by weight based on the weight of a basepolymer is very effective as a resist.

Even the composition having no sensitizing agent has sufficientsensitivity for use as a resist for an electron beam. Therefore, unlessvery high sensitivity is required, it is effective to use a base polymercontaining no sensitizing agent as a one-component resist so that theexcellent property of the polymer may be fully utilized.

The characteristics of the composition having sensitivity to light orradiation will now be described. First, the resist material of thepresent invention has the high silicon content as shown in FIG. 9. Inparticular, the resist material (sample 11) shown in FIG. 2 has thesilicone content close to that of a silicon dioxide film (SiO₂), therebyproviding high resistance to plasma. This may improve the selectionratio during a process of etching, and therefore a resist pattern may betransferred with high resolution.

FIG. 10 shows the light transmittance of the resist material of thepresent invention, wherein the full line represents the lighttransmittance of a sample 11 with a film thickness of 1 μm, and thebroken line denotes the light transmittance of a sample 21 with a filmthickness of 1 μm.

Sample 21 has high light transmittance in a wide range from visiblelight to medium ultraviolet rays while absorbing light of a wavelengthof 300 nm or less according to a phenyl group thereof. On the otherhand, sample 11 has high light transmittance of all the range fromvisible light to far ultraviolet rays. Thus, the resist material of thepresent invention has high light transmittance. This is attributed tothe fact that the base polymer made of a framework of the siloxane bondshas high light transmittance to ultraviolet rays and that theconcentration of sensitizing agent can be restricted to a lowerconcentration degree because the resist material utilizes the chemicallysensitizable reaction.

FIG. 11 shows the results of thermogravimetric analysis, wherein thefull line represents the value of sample 11 with a film thickness of 1μm, and the broken line denotes the value of polyimide with a filmthickness of 1 μm.

These samples are hardened at 200° C. for 30 minutes, after which howthe weight of the samples decreases during the heat treatment is shown.

The weight of sample 11 scarcely decreases at temperatures up to 500°C., and slightly decreases even at 500° C. or more. This decrease inweight of the sample occurs because the methyl groups at the side chainsgroups are dissociated from the polymer of the sample. Polyimide hasbeen widely used as conventional heat-resistant polymer material. FIG.11 clearly shows that the resist of the present invention has higherheat resistance compared with polyimide. Sample 11 is used to prepare aresist pattern by exposure and development. The resulting resist patternis heated, after which the thermal deformation of the resist pattern isobserved. However, at temperatures up to 300° C., no thermal deformationof the resist pattern can be observed. On the other hand, the resistpattern of a conventional photoresist begins to deform at about 120° C.Consequently, the resist pattern of the present invention is found topossess remarkedly high thermal resistance.

As compared with other organic film, since the resist of the presentinvention is mainly composed of polysiloxane, it has high electricalinsulating property, high hardness, excellent water resisting property,low hygroscopic property, high adhesion to a metal substrate or asilicon substrate, and further high capability of leveling the unevensurface of a substrate.

As described above, the composition having sensitivity to light orradiation of the present invention has sensitivity to light, togetherwith high plasma resistance, high light transmittance, high thermalresistance, high electrical insulating property, high hardness, highwater resisting property, low hygroscopic property, high adhesion, andhigh smoothing capability. Therefore, the resist has not only a use fora resist material for preparing fine elements but also various otheruses.

The method for manufacturing a semiconductor device will now bedescribed wherein the composition having sensitivity to light orradiation of the present invention is used as a resist material.

First, the case will be described in detail by reference to FIG. 12,where the composition having sensitivity to light or radiation of thepresent invention is used as an upper resist in a two-layer resistmethod for an electron beam lithography.

To a semiconductor substrate having uneven surface 1 is applied topolyimide with a thickness of 2 μm. Thereafter, the polyimide film isheat treated at 200° C. to form a smoothing layer 2, to which is appliedthe resist material of the present invention with a thickness of 0.25 μm(FIG. 12(a)).

In this case, the resist material shown in FIG. 2 is used whereinpolymethylsilsesquioxane having a siloxane-bond structure which containsa methyl group as a side chain group and a hydroxyl group and an ethoxygroup as an end group is a base polymer, and triphenylsulfonium triflateis a sensitizing agent. The number average molecular weight and theweight average molecular weight of polymethylsilsesquioxane are 3,273and 7,044, respectively, and the concentration of sensitizing agentcontent is 2 percent by weight.

Next, the predetermined portions of the resist film are exposed to anelectron beam at an exposure amount of 0.3 μC/cm², after which theresist is developed in a 2.38% solution of TMAH (FIG. 12(b)).

Further, the smoothing layer 2 is etched by means of dry etching by theuse of oxygen. In this process, an upper layer with a resist pattern isused as a mask for dry etching, and the pattern at the predeterminedportions exposed to an electron beam is transferred to the lowersmoothing layer 2 (FIG. 12(c)). This method may provide a pattern with awidth of 0.3 μm on a semiconductor substrate having a difference inlevel of 1 μm by a low exposure amount rate of 0.3 μC/cm².

Secondly, the method for preparing a phase shifting mask will bedescribed in detail by reference to FIGS. 13 and 14, wherein thecomposition having sensitivity to light or radiation of the presentinvention is used as a resist material.

The phase shifting mask is obtained by improving a photomask for use inexposure by means of a conventional projection and exposure apparatus inorder to form a fine pattern. Thus, a method is for forming a finerresist pattern by imparting a phase difference to light from an optimalsystem which is used in exposure. Examples of the method utilizing sucha photomask (hereinafter, referred to as a phase shifting mask) aredescribed in Japanese Laid-Open Patent Publication No. 62-50811,Japanese Laid-Open Patent Publication No. 62-59296, etc.

According to the method herein proposed, the original picture of apattern to be transferred to a photomask substrate is made of a lightnon-transmissive film. A phase shifter having a pattern on a transparentfilm is provided on either of transparent portions having a pattern.These transparent portions hold the light non-transmissive film betweenthem or are formed at both sides of the light non-transmissive film. Thephase shifter changes the phase of light to be exposured.

However, the above phase shifter for use in a conventional photomaskneeds to be transparent with respect to light having wavelength up tothat of ultraviolet rays. On handling the photomask, it is desirablethat the phase shifter has high hardness, and high resistance to shock,and furthermore, has excellent thermal resistance and chemicalresistance for washing thereof when dust, etc., deposit thereover.Moreover, the phase shifter is required to have high water resistingproperty, low hygroscopic property, and high adhesion to a substrate,concerning washing.

The process for forming a phase shifter will now be described, whereinthe composition having sensitivity to light or radiation of the presentinvention is used as a resist material.

FIG. 13(a) shows a photomark comprising a chrome film with a pattern 5on a quartz substrate 4.

To the above mask is applied the composition having sensitivity to lightor radiation of the present invention as a resist material with athickness of 0.53 μm (FIG. 13(b)).

In this case, polymethylsilsesquioxane having a siloxane-bond structurewhich contains a methyl group as a side chain group and a hydroxyl groupand an ethoxy group as an end group is used as a resist material. Theweight average molecular weight of this resist material is 7,044. Theresist material containing no sensitizing agent is used so as to avoidthe adsorption of ultraviolet rays by the sensitizing agent.

This resist film is heat treated at 70° C., after which the treated filmis exposed to an electron beam at a rate of 25 μC/cm², and thendeveloped by the use of a 2.38% solution of TMAH to form a resistpattern (FIG. 13(c)).

When the resist of the present invention is exposed to an electron beam,a lamination of the chrome film with a pattern and a resist pattern areexposed based on detection of the positioning mark on the chrome film.

Moreover, the heat-treatment of this mask substrate at 200° C. completesthe reaction of the end group of the pre-polymerization polymer (--OH,--C₂ H₅ OH), thereby stabilizing the resist.

The resist thus prepared is used as a phase shifter 6. As describedbefore, this resist is transparent to light having wavelength up to thatof ultraviolet rays, and has high thermal resistance and chemicalresistance, and concerning washing has further properties of high waterresisting property, low hygroscopic property, and high adhesion to asubstrate.

As described above, the phase shifting mask may be prepared in a easyprocess as shown in FIG. 13.

FIG. 14 shows the construction of another phase shifting mask by the useof the resist of the present invention as a phase shifter.

FIG. 14(a) shows a Levenson type phase shifting mask comprising thephase shifter 6 arrayed at every other groove of the chrome film with apattern 5.

FIG. 14(b) shows a transparent type phase shifting mask comprising onlya phase shifter 6 which has a pattern formed by said phase shifter.

FIG. 14(c) shows an emphasized-edge type phase shifting mask comprisingthe phase shifter 6 arrayed at a predetermined distance from the grooveof the chrome film with a pattern 5.

Hitherto, a silicon dioxide film (SiO₂) or a coated oxide film (SOG) hasbeen used as the phase shifter of a phase shifting mask. According tothe method by the use of this conventional phase shifter, a resistpattern is formed on a silicon dioxide film or a SOG film, and by theuse of the resulting resist pattern as a mask, a phase shifting patternis formed by dry etching. This conventional method involves acomplicated manufacturing process, accompanied with increased defectivedensity.

According to the aforesaid method wherein the resist of the presentinvention is used for a phase shifting mask, the pattern of the phaseshifter 6 can be directly drawn by means of an electron beam, therebylargely simplifying the process for preparing a phase shifting mask.

The case where the composition having sensitivity to light or radiationof the present invention is used as a chip covering material of asemiconductor device will now be described in detail by reference toFIG. 15.

As shown in FIG. 15(a), semiconductor elements are provided on thesilicon substrate 1. All the surface of a silicon substrate 1 except theportions where bonding pads 8 made of an aluminum film is formed, iscovered by a silicon nitride film used as a protective coat 7, therebyopening windows of the protective coat at the bonding pad portions.

The resist material of the present invention is applied to this coatedsubstrate 1 with a thickness of 3.5 μm, after which the resulting filmis heat treated at 70° C. (FIG. 15(b).

In this case, a composition is used as a resist material, whereinpolyphenylsilsesquioxane having a siloxane-bond structure which containsa phenyl group as a side chain group and a hydroxyl group and an ethoxygroup as an end group is a base polymer, diphenyliodonium triflate is asensitizing agent, and perylene is a sensitizer.

The resist film is exposed to light by means of a stepper utilizing ag-line at a exposure amount of 60 mJ/cm², after which the irradiatedfilm is developed by the use of a 5% TMAH solution to leave the resistfilm on the circuit portions on the semiconductor substrate 1 (FIG.15(c)).

Further, an open window at the bonding pads 8 on the substrate 1 isconnected to gold wires 9 by wire-bonding, thereby completing asemiconductor device.

As stated above, since this resist material has high thermal resistanceas well as high chemical resistance, it may be directly used as a chipcovering material.

Polyimide has been used as a conventional chip covering material. Inorder to open a window on a polyimide film for bonding pads, a resistpattern should be formed on the polyimide film, and then the polyimidefilm should be etched by means of wet etching through the resist patternas a mask.

While the above conventional method involves a complicated manufacturingprocess, the use of the resist material of the present invention has achip covering material enables a window to be opened by exposure toultraviolet rays, thereby largely simplifying the process.

Since this resist has high transparency to light including ultravioletrays as stated above, it is particularly effective as a window materialfor EPROM (erasable programmable read-only memory) wherein data iserased by irradiation with ultraviolet rays.

As stated above, the composition having sensitivity to light orradiation of the present invention may be applied for various materialsbesides a resist material for use in an upper resist film of a two-layerresist, a chip covering material on a protective coat of a semiconductordevice, a material for constituting a phase shifting film for a phaseshifting mask.

For example, the composition of the present invention may be used as amaterial of a micro lens for use in converging light from CCD, amaterial for constituting an α-rays cutoff film of a semiconductorelement, a protective coat material of a semiconductor device, a layerinsulation film material for multilayer inter-connection, a smoothinglayer material for multilayer inter-connection of a semiconductordevice, a smoothing material of a bubble memory device, an insulatinglayer material of a thin film magnetic head, etc.

When the composition of the present invention is used for the abovematerials, a pattern may be directly formed by exposure as mentioned inExamples, and it is necessary to denote that the resulting pattern hashigh resistance to plasma, high transparency, high thermal resistance,high electric insulating property, high hardness, high water resistingproperty, low hygroscopic property, high adhesion to substrate, highsmoothing capability, etc.

The Examples mentioned above, illustrate the exposure of predeterminedpattern to ultraviolet rays or an electron beam. The light source is notlimited to those used in the Examples, the use of an ion beam or anX-ray may be possible.

It is understood that various other modifications will be apparent toand can be readily made by those skilled in the art without departingfrom the scope and spirit of this invention. Accordingly, it is notintended that the scope of the claims appended hereto be limited to thedescription as set forth herein, but rather that the claims be construedas encompassing all the features of patentable novelty that reside inthe present invention, including all features that would be treated asequivalents thereof by those skilled in the art to which this inventionpertains.

What is claimed is:
 1. A process for forming a pattern, comprising thesteps of:forming a smoothing layer on a substrate; applying acomposition having sensitivity to light or radiation to said smoothinglayer to form a resist film, wherein said composition consistsessentially of a polymer having a siloxane-bond structure and having atleast one end group or a side chain group, and a sensitizing agent, eachof said end group and said side chain group is a functional group whichcauses condensation polymerization upon exposure to acid; and exposing aportion of said resist film to light or radiation, thereby causing saidsensitizing agent to provide an acid which causes condensationpolymerization at said end group or said side chain group of saidpolymer; and developing said resist film by the use of an alkalideveloper.
 2. A process for forming a pattern, comprising the stepsof:forming a smoothing layer on a substrate; applying a compositionhaving sensitivity to light or radiation to said smoothing layer to forma resist film, wherein said composition consists essentially of apolymer having a siloxane-bond structure and having at least one endgroup or a side chain group, a sensitizing agent, and a dye having highsolubility in a polar solvent, each of said end group and said sidechain group is a functional group which causes condensationpolymerization upon exposure to acid; exposing a portion of said resistfilm to light or radiation, thereby causing said sensitizing agent toproduce an acid which causes condensation polymerization at said endgroup or said side chain group of said polymer; and developing saidresist film by the use of an alkali developer.
 3. A process for forminga pattern, comprising the steps of:forming a smoothing layer on asubstrate; applying a composition having sensitivity to light orradiation to said smoothing layer to form a resist film, wherein saidcomposition consists essentially of a polymer having a siloxane-bondstructure and a sensitizing agent, said polymer having a structureselected from the group of structures represented by the followinggeneral formula: ##STR3## wherein R¹, R², R³, and R⁴ are independently ahydrogen atom, a hydroxyl group, a lower alkyl group having 1 to 5carbon atoms, a lower alkoxyl group having 1 to 5 carbon atoms, or atrialkylsilyl group; at least one group selected from the groupconsisting of R³ and R⁴ is a lower alkoxyl group having 1 to 5 carbonatoms; and n1 is an integer of 1 or more; exposing a portion of saidresist film to light or radiation, thereby causing said polymer toundergo a polymerization reaction; and developing said resist film bythe use of an alkali developer.
 4. A process for forming a pattern,comprising the steps of:forming a smoothing layer on a substrate;applying a composition having sensitivity to light or radiation to saidsmoothing layer to form a resist film, wherein said composition consistsessentially of a polymer having a siloxane-bond structure and asensitizing agent, said polymer having a structure selected from thegroup of structures represented by the following general formula:##STR4## wherein R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are independently ahydrogen atom, a hydroxyl group, a lower alkyl group having 1 to 5carbon atoms, a lower alkoxyl group having 1 to 5 carbon atoms, or atrialkylsilyl group; at least one group selected from the groupconsisting of R⁷, R⁸, R⁹, and R¹⁰ is a lower alkoxyl group having 1 to 5carbon atoms; and n2 is an integer of 1 or more; exposing a portion ofsaid resist film to light or radiation, thereby causing said polymer toundergo a polymerization reaction; and developing said resist film bythe use of an alkali developer.
 5. A process for forming a pattern,comprising the steps of:forming a smoothing layer on a substrate;applying a composition having sensitivity to light or radiation to saidsmoothing layer to form a resist film, wherein said composition consistsessentially of a polymer having a siloxane-bond structure and asensitizing agent, said polymer having a structure selected from thegroup of structures represented by the following general formula:##STR5## wherein R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, and R¹⁸ areindependently a hydrogen atom, a hydroxyl group, a lower alkyl grouphaving 1 to 5 carbon atoms, a lower alkoxyl group having 1 to 5 carbonatoms, or a trialkylsilyl group; at least one group selected from thegroup consisting of R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, and R¹⁸ is alower alkoxyl group having 1 to 5 carbon atoms; and n3 and m areindependently integers of 1 or more; exposing a portion of said resistfilm to light or radiation, thereby causing said polymer to undergo apolymerization reaction; and developing said resist film by the use ofan alkali developer.
 6. A method for preparing a photomask, comprisingthe steps of:applying a light non-transmissive pattern on a surface of asubstrate; applying a composition over the surface of said substratewith said light non-transmissive pattern to form a resist film, whereinsaid composition has sensitivity to light or radiation, and consistsessentially of a polymer having a siloxane-bond structure, said polymerhaving a structure selected from the group of structures represented bythe following general formula: ##STR6## wherein R¹, R², R³, and R⁴ areindependently a hydrogen atom, a hydroxyl group, a lower alkyl grouphaving 1 to 5 carbon atoms, a lower alkoxyl group having 1 to 5 carbonatoms, or a trialkylsilyl group; at least one group selected from thegroup consisting of R³ and R⁴ is a lower alkoxyl group having 1 to 5carbon atoms; and n1 is an integer of 1 or more; exposing a portion ofsaid resist film to light or radiation, thereby causing said polymer toundergo a polymerization reaction; and developing said resist film bythe use of a developer, resulting in a phase shifter.
 7. A method ofclaim 6, which further comprises the step of subjecting the phaseshifter to a heating treatment to complete a polymerization reaction ofthe polymer contained in the composition.
 8. A method for preparing aphotomask, comprising the steps of:applying a light non-transmissivepattern on a surface of a substrate; applying a composition over thesurface of said substrate with said light non-transmissive pattern toform a resist film, wherein said composition has sensitivity to light orradiation, and consists essentially of a polymer having a siloxane-bondstructure, said polymer having a structure selected from the group ofstructures represented by the following general formula: ##STR7##wherein R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are independently a hydrogen atom, ahydroxyl group, a lower alkyl group having 1 to 5 carbon atoms, a loweralkoxyl group having 1 to 5 carbon atoms, or a trialkylsilyl group; atleast one group selected from the group consisting of R⁷, R⁸, R⁹, andR¹⁰ is a lower alkoxyl group having 1 to 5 carbon atoms; and n2 is aninteger of 1 or more; exposing a portion of said resist film to light orradiation, thereby causing said polymer to undergo a polymerizationreaction; and developing said resist film by the use of a developer,resulting in a phase shifter.
 9. A method of claim 8, which furthercomprises the step of subjecting the phase shifter to a heatingtreatment to complete a polymerization reaction of the polymer containedin the composition.
 10. A method for preparing a photomask, comprisingthe steps of:applying a light non-transmissive pattern on a surface of asubstrate; applying a composition over the surface of said substratewith said light non-transmissive pattern to form a resist film, whereinsaid composition has sensitivity to light or radiation, and consistsessentially of a polymer having a siloxane-bond structure, said polymerhaving a structure selected from the group of structures represented bythe following general formula: ##STR8## wherein R¹¹, R¹², R¹³, R¹⁴, R¹⁵,R¹⁶, R¹⁷, and R¹⁸ are independently a hydrogen atom, a hydroxyl group, alower alkyl group having 1 to 5 carbon atoms, a lower alkoxyl grouphaving 1 to 5 carbon atoms; or a trialkylsilyl group; at least one groupselected from the group consisting of R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷,and R¹⁸ is a lower alkoxyl group having 1 to 5 carbon atoms; and n3 andm are independently integers of 1 or more; exposing a portion of saidresist film to light or radiation, thereby causing said polymer toundergo a polymerization reaction; and developing said resist film bythe use of a developer, resulting in a phase shifter.
 11. A method ofclaim 10, which further comprises the step of subjecting the phaseshifter to a heating treatment to complete a polymerization reaction ofthe polymer contained in the composition.
 12. A method for preparingsemiconductor devices comprising the steps of:forming a semiconductorelement on a surface of a substrate; forming a plurality of bonding padson part of the substrate; forming a protective film to cover the surfaceof the substrate; subjecting the protective film to an etching treatmentto form windows on the portions of the protective film facing theindividual bonding pads; applying a composition to the protective filmincluding the bonding pads, resulting in a resist film, wherein saidcomposition has sensitivity to light or radiation, and consistsessentially of a polymer having a siloxane-bond structure and having atleast one end group or a side chain group, and a sensitizing agent, eachof said end group and said side chain group is a functional group whichcauses condensation polymerization upon exposure to acid; exposing saidresist film to light or radiation, thereby causing said sensitizingagent to produce an acid which causes condensation polymerization atsaid end group or said side chain group of said polymer; developing saidresist film by the use of a developer; and connecting the individualbonding pads to wires.
 13. A method for preparing semiconductor devicescomprising the steps of:forming a semiconductor element on a surface ofa substrate; forming a plurality of bonding pads on part of thesubstrate; forming a protective film to cover the surface of thesubstrate; subjecting the protective film to an etching treatment toform windows on the portions of the protective film facing theindividual bondings pads; applying a composition to the protective filmincluding the bonding pads, resulting in a resist film, wherein saidcomposition has sensitivity to light or radiation, and consistsessentially of a polymer having a siloxane-bond structure and having atleast one end group or a side chain group, a sensitizing agent, and adye having high solubility in a polar solvent, each of said end groupand said side chain group is a functional group which causescondensation polymerization upon exposure to acid; exposing said resistfilm to light or radiation, thereby causing said sensitizing agent toproduce an acid which causes condensation polymerization at said endgroup or said side chain group of said polymer; developing said resistfilm by the use of a developer; and connecting the individual bondingpads to wires.
 14. A method for preparing semiconductor devicescomprising the steps of:forming a semiconductor element on a surface ofa substrate; forming a plurality of bonding pads on part of thesubstrate; forming a protective film to cover the surface of thesubstrate; subjecting the protective film to an etching treatment toform windows on the portions of the protective film facing theindividual bonding pads; applying a composition to the protective filmincluding the bonding pads, resulting in a resist film, wherein saidcomposition has sensitivity to light or radiation, and consistsessentially of a polymer having a siloxane-bond structure and asensitizing agent, said polymer having a structure selected from thegroup of structures represented by the following general formula:##STR9## wherein R¹, R², R³, R⁴ are independently a hydrogen atom, ahydroxyl group, a lower alkyl group having 1 to 5 carbon atoms, a loweralkoxyl group having 1 to 5 carbon atoms, or a trialkylsilyl group; atleast one group selected from the group consisting of R³ and R⁴ is alower alkoxyl group having 1 to 5 carbon atoms; and n1 is an integer of1 or more; exposing said resist film to light or radiation, therebycausing said polymer to undergo a polymerization reaction; developingsaid resist film by the use a developer; and connecting the individualbonding pads to wires.
 15. A method for preparing semiconductor devicescomprising the steps of:forming a semiconductor element on a surface ofa substrate; forming a plurality of bonding pads on part of thesubstrate; forming a protective film to cover the surface of thesubstrate; subjecting the protective film to an etching treatment toform windows on the portions of the protective film facing theindividual bonding pads; applying a composition to the protective filmincluding the bonding pads, resulting in a resist film, wherein saidcomposition has sensitivity to light or radiation, and consistsessentially of a polymer having a siloxane-bond structure and asensitizing agent, said polymer having a structure selected from thegroup of structures represented by the following general formula:##STR10## wherein R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are independently ahydrogen atom, a hydroxyl group, a lower alkyl group having 1 to 5carbon atoms, a lower alkoxyl group having 1 to 5 carbon atoms, or atrialkylsilyl group; at least one group selected from the groupconsisting of R⁷, R⁸, R⁹, and R¹⁰ is a lower alkoxyl group having 1 to 5carbon atoms; and n2 is an integer of 1 or more; exposing said resistfilm to light or radiation, thereby causing said polymer to undergo apolymerization reaction; developing said resist film by the use adeveloper; and connecting the individual bonding pads to wires.
 16. Amethod for preparing semiconductor devices comprising the stepsof:forming a semiconductor element on a surface of a substrate; forminga plurality of bonding pads on part of the substrate; forming aprotective film to cover the surface of the substrate; subjecting theprotective film to an etching treatment to form windows on the portionsof the protective film facing the individual bonding pads; applying acomposition to the protective film including the bonding pads, resultingin a resist film, wherein said composition has sensitivity to light orradiation, and consists essentially of a polymer having a siloxane-bondstructure and a sensitizing agent, said polymer having a structureselected from the group of structures represented by the followinggeneral formula: ##STR11## wherein R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷,and R¹⁸ are independently a hydrogen atom, a hydroxyl group, a loweralkyl group having 1 to 5 carbon atoms, a lower alkoxyl group having 1to 5 carbon atoms, or a trialkylsilyl group; at least one group selectedfrom the group consisting of R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶, R¹⁷, and R¹⁸is a lower alkoxyl group having 1 to 5 carbon atoms; and n3 and m areindependently integers of 1 or more; exposing said resist film to lightor radiation, thereby causing said polymer to undergo a polymerizationreaction; developing said resist film by the use of a developer; andconnecting the individual bonding pads to wires.